Hypoxic–Ischemic Encephalopathy (Preterm, Term, and Adult)

Abstract

Hypoxic–ischemic injury (HII) to the brain is usually a devastating event and an important cause of morbidity and mortality in the United States and elsewhere in the world. Neuroimaging plays a pivotal role in diagnosis, treatment, and long-term prognosis determination for these patients. The correct diagnosis made on the basis of different imaging modalities requires knowledge of the different manifestations of this type of injury. Some of the factors that contribute to the different findings are brain maturity, duration and severity of the insult, underlying cause, and associated disorders.

Severe HII will result in preferentially deep gray matter damage in preterm and term infants, with peri-rolandic involvement more frequently observed in the latter age group. In these patients, a less profound insult will result in germinal matrix hemorrhages or periventricular leukomalacia (PVL) in preterm neonates and parasagittal watershed infarcts in term neonates. In the postnatal period, severe insults produce diffuse gray matter injury, with relative sparing of the peri-rolandic cortex and posterior circulation structures. In older children and adults, profound insults produce injury in the deep gray matter nuclei, cortices, hippocampi, and cerebellum.

The use of advanced MRI techniques such as DWI and MR spectroscopy is useful in making the diagnosis especially in the acute setting where conventional imaging might be less sensitive.